1. Field of the Invention
The invention relates to a track and hold amplifier, and more particularly to an analog to digital converter with a front-end track and hold amplifier.
2. Description of the Related Art
Currently, analog to digital (A/D) converters are widely used in a variety of applications, such as medical systems, audio systems, test and measurement equipment, communication systems, and image and video systems, etc.
A track and hold amplifier is often considered the front-end of an A/D converter. The ideal purpose of the track and hold amplifier is to track an analog input signal and, at specified times, to hold that signal at its output until the held signal is received by other circuits of the A/D converter, such that the A/D converter can accurately convert the analog input signal to a digital signal. However, in fact, an inherent nonlinearity of an amplifier or a buffer that is used in the track and hold amplifier will degrade the resolution of the A/D converter such that the digital signal can not accurately represent the analog input signal.
Thus, calibrating nonlinearity of a track and hold amplifier in an A/D converter is desired.